Construction of highly-stable covalent organic framework with combined enol-imine and keto-enamine linkages

A novel covalent organic framework (COF) (Tp-BI-COF) with combined ketimine-type enol-imine and keto-enamine linkages was prepared through a cascade of ketimine condensation followed by aldimine condensation and characterized by XRD, solid state 13C NMR, IR, TGA and BET. Tp-BI-COF showed high stability toward acid, organic solvent, and boiling water. The 2D COF exhibited photochromic properties after being irradiated with a xenon lamp. The stable COF, with aligned one-dimensional nanochannels, provided nitrogen sites on pore walls, which confine and stabilize the H3PO4 in the channel via hydrogen-bonding interactions. After loading with H3PO4, the material showed excellent anhydrous proton conductivity.


S-3 Structure Modeling and Atomic Coordinates of COFs S9
S-4 FT-IR Spectra S17

S-14 Nyquist plots of H 3 PO 4 @Tp-BI-COF S32
S3 performed on a PerkinElmer 2400chn elemental analyzer. SEM images were obtained using a JSM-6480LV at 5.0 kV. FEI (Jeol FEG 2100F) high resolution transmission electron microscope (HRTEM) equipped with field emission source operating at 300 kV was used to record TEM images. The nitrogen adsorption and desorption isotherms were measured at 77 K using an Autosorb-iQ (Quantachrome) surface area size analyzer. Before measurement, the samples were degassed in vacuum at 100 °C for 10 h. The Brunauer-Emmett-Teller (BET) method was utilized to calculate the specific surface area. 1

Preparation of H 3 PO 4 @Tp-BI-COF: H 3 PO 4 @Tp-BI-COF was prepared according
to a reported method. 4 Homogeneous solution of phosphoric acid crystal (148.63 mg) dissolved in anhydrous THF (2 mL) was injected into the Tp-BI-COF sample (50 mg) in a vial (20 mL) which was preheated under vacuum at 120 °C overnight to yield a solution which was stirred at room temperature for 3 h under N 2 . The system was slowly evaporated under vacuum to remove THF at 70 °C over a period of 6 h. The vial was then kept in an oven at 70 °C under N 2 for 12 h. The resulting powder was collected to yield H 3 PO 4 @Tp-BI-COF quantitatively.

Stability test and COF sample recovery methods.
Stability test: The COF samples (100 mg) were dispersed in different solvents including water (100 °C), THF, CH 2 Cl 2 , aqueous HCl (9 M), and neat H 3 PO 4 (9 M, a THF solution of H 3 PO 4 ), and stirred for one week. Stability in base circumstance was tested in aqueous NaOH solution by dispersing COF sample (100 mg) into aqueous NaOH (9 M) and stirring for one or two days.

Sample recovery methods:
The COF samples in boiling water, THF, and CH 2 Cl 2 were collected by filtration and dried at 120 °C under vacuum for 12 h. The COF samples in THF solution of H 3 PO 4 was washed with CH 3 OH (2 × 10 mL) and water (10 × 10 mL), neutralized with triethylamine/acetone solution (5 %, 1 × 10 mL), washed again with water (5 × 10 mL) and dried under vacuum at 120 °C for 12 h. The COF sample in the aqueous HCl solution was washed with water (5 × 10 mL), neutralized with triethylamine/acetone solution (5 %, 1 × 10 mL), washed again with water (5 × 10 mL), and dried under vacuum at 120 °C for 12 h. COF sample in aqueous NaOH solution was washed with water (20 × 10 ml) and dried under vacuum at 120 °C for 12 h. These samples were then used for PXRD and porosity measurements.

Section S-3: Structure Modeling and Atomic Coordinates of COF
The geometry of compound BI was optimized with Materials Studio suite of programs to determine the conformations. Simulation was started from likely conformation and minimized using universal force-field in the forcite module.
The Tp-BI-COF models were simulated using Materials Studio suite of programs.
Firstly, the eclipsed model was built and the symmetry of lattice was degraded to P1.
Then the lattice and geometry model were optimized using universal force-field in the forcite module. The staggered arrangement for Tp-BI-COF was also examined by offsetting the alternating stacked units from the eclipsed model.
Pawley refinement was carried out using Reflex module, a software package for crystal determination from PXRD pattern. Unit cell dimension was set to the theoretical parameters. The Pawley refinement was performed to optimize the lattice parameters iteratively until the Rwp value converges and overly of the observed with refined profiles show good agreement.  obtained. There may well be additional conformation, but these are representative.